As a typical metal-free layered organic semiconductor photocatalyst, carbon nitride suffers from low light harvesting ability and unsatisfied photocatalytic activity ascribed to insufficient optical absorption and strongly bound exciton. In this paper, we reported the fabrication of a well crystallized carbon nitride with superior visible-light-driven photoreactivity by simply polymerization of dicyandiamide in a closed stainless steel autoclave which is used to afford a high pressure reaction environment. High pressure induced polymerization of dicyandiamide not only prevents the emission of hazardous gas, improving the yield of carbon nitride, but also enhances the crystallization of carbon nitride. The 550 °C calcined sample at high pressure (HP550) extends the interplanar packing distance of layered carbon nitride from 0.676 nm to 0.697 nm while compacts the layered-stacking distance from 0.327 nm to 0.322 nm when compared its counterpart that was synthesized under other identical conditions but at normal pressure (NP550). HP550 exhibits the highest photocatalytic activity towards hydrogen production (772.40 umol⁻¹h⁻¹g⁻¹) under visible light irradiation (λ ≥ 420 nm), which is 7.8 times higher than that of NP550. The drastic improved photocatalytic activity of carbon nitride prepared at high pressure was attributed to the negatively shifted position of conductor band potentials, increased visible-light absorption and efficient separation of charge carriers, benefiting from the reduced π–π layer stacking distance and breaking of intraplanar hydrogen bonds.

作为典型的无金属的层状有机半导体光催化剂，氮化碳具有低的光收集能力和由于不充分的光吸收和强烈结合的激子而不能满足的光催化活性。在本文中，我们报道了通过在封闭的不锈钢高压釜中简单地聚合双氰胺来制造具有良好可见光驱动的光反应性的结晶良好的氮化碳，该高压釜用于提供高压反应环境。高压诱导的双氰胺的聚合反应不仅可以防止有害气体的排放，提高氮化碳的收率，而且可以增强氮化碳的结晶。在550°C的高压下煅烧的样品（HP550）将层状氮化碳的面内堆积距离从0.676 nm扩展到0。与在其他相同条件下但在常压下合成的对应物（NP550）相比，697 nm可使层状堆叠距离从0.327 nm压缩至0.322 nm。HP550对制氢表现出最高的光催化活性（772.40 umol^-1 h ^-1 g ^-1）在可见光照射下（λ≥420 nm），是NP550的7.8倍。高压制备的氮化碳的光催化活性得到极大改善，这归因于导体带电势的负向偏移，可见光吸收增加和电荷载流子的有效分离，这得益于减小的π-π层堆叠距离和平面内破裂氢键。